This invention relates to a cement based patching composition and, in particular, to a patching composition which incorporates cement, a dispersible latex polymer binder, a mineral aggregate filler and an elastromeric filler, and a method for using same in paving, repairing or filling depressions in asphalt pavement.
Because of degradation due to use and weather, repair of asphalt or bituminous pavement as always been a great concern for those who must maintain highways, roads and parking areas. As used herein, the terms "asphalt" and "bituminous" shall be used interchangeably to refer to pavement surfaces in which bitumen-containing materials are employed as a base for the pavement. Repair of such pavements is also of great concern to the average homeowner or small business owner who cannot easily and inexpensively obtain the material and equipment need for conventional hot or cold asphalt patching. At most, only common hand tools and equipment are available to effect such repairs.
Bitumen emulsions and bitumen emulsions containing mineral fillers are sometimes used to filling depressions in asphalt surfaces. While these materials may be easily applied with hand tools, they are generally not suitable in applications where filling is required to a depth greater than one-half inch. Another product, "Asphalt Repair" manufactured by Set Consumer Products, Inc., comprises black pigmented magnesium phosphate concrete and may be used for repair of asphalt pavement in thicknesses greater than one-half inch. However, this product is generally not useful in applications of lower thickness or for applying a feather edge to a patch, and does not exhibit flexibility conforming substantially to the surrounding asphalt pavement.
Concrete mixes consisting generally in excess of 12-15% portland cement, the balance being sand and/or stone aggregate, are sometimes employed to patch depressions, holes or cracks in asphalt pavement. Such products are generally easily prepared by mixing with water, utilizing conventional hand tools, and do not require any specialized equipment or techniques to apply. However, cementitious materials such as concrete mixes normally do not bond sufficiently to asphalt, nor do they exhibit enough flexibility to conform to the deformation encountered on asphalt pavement surfaces.
Other prior art patching and paving compositions are disclosed in U.S. Pat. No. 2,773,777 to Alexander et al., U.S. Pat. No. 4,021,393 to McDonald and U.S. Pat. No. 2,841,060 to Coppage. The Alexander et al. patent discloses a bituminous composition suitable for use in construction surfaces such as roadway, foot paths, floor, or runways, which comprises a selected mineral aggregate, bitumen, portland cement and a small amount of at least one water soluble polyvalent metal salt of a strong mineral acid. McDonald discloses an elastromeric paving material which incorporates ground rubber into asphalt, while Coppage discloses a so-called "bituminous concrete" paving composition in which a natural or synthetic rubber aqueous dispersion is injected into a heat-liquified bituminous material. However, these latter two compositions are required to be heated prior to application.
Bearing in mind the problems and deficiencies in the prior art and long felt needs, it is therefore an object of the present invention to provide an improved, bitumen-free patching composition which is compatible with asphalt paving.
It is another object of the present invention to provide a paving or patching composition which may be applied using conventional hand tools.
It is a further object of the present invention to provide a paving or patching composition which is available in dry, granular form and may be mixed with water at the work site.
It is yet another object of the present invention to provide a bitumen-free patching composition which is compatible in flexibility and other properties with asphalt paving and which bonds tightly to the asphalt pavement.
It is a further object of the present invention to provide an improved paving and patching composition which meets the aforestated objects, yet which is relatively inexpensive to manufacture and easy to apply to pavement without heating.
It is yet another object of the present invention to provide a long lasting, durable, flexible patching composition which blends in with the surrounding asphalt pavement.